Device for fastening flexible printing plates

ABSTRACT

A plate lock-up mechanism for securing and adjusting a flexible printing plate upon a plate cylinder which includes a supporting plate flatly seated in a groove formed in the cylinder and which extends the length of the groove. Mounting bars are spaced end to end above the supporting plate, each of the mounting bars having a clamping rail for holding the edge of a printing plate and the mounting bars being captively shiftable on the supporting plate. Each mounting bar has provision for circumferential and axial adjustment. The supporting plate is clamped in the bottom of the groove by readily accessible screws which permit removal, as a unit, of the supporting plate, the captive mounting bars, and associated parts. This permits substitution of an alternative single, elongated mounting bar for accommodating a single plate which extends the length of the groove.

United States Patent Abendroth DEVICE FOR FASTENING FLEXIBLE PRINTINGPLATES [75] Inventor: Paul Abendroth, Offenbach,

Germany [73] Assignee: Roland Offsetmaschinenfabrik Faber & SchleicherAG, Germany [22] Filed: May 21, 1973 [21] Appl. No.: 362,182

[30] Foreign Application Priority Data May 26, 1972 Germany 2225333 [52]US. Cl 101/415.1; 101/378 [51] Int. Cl B4lf 27/12 [58] Field of Search101/415,1, 378

[56] References Cited UNITED STATES PATENTS 2,271,160 1/1942 Huck10l/415.l 3,151,553 10/1964 Norton.... 101/415.1 3,154,012 10/1964Fischer... l01/415.l 3,168,040 2/1965 Norton.... 101/415.1 3,188,9526/1965 Miller 101/415.1

3,424,085 1/1969 Beisel 10l/415.l 3,460,443 8/1969 Sarka et al.101/415.1 X

3,557,695 1/1971 Preuss l0l/415.l

Primary Examiner-Edgar S. Burr Assistant Examiner-Paul J. HirschAttorney, Agent, or Firm-Wolfe, Hubbard, Leydig, Voit & Osann, Ltd.

[5 7 ABSTRACT A plate lock-up mechanism for securing and adjusting aflexible printing plate upon a plate cylinder which includes asupporting plate flatly seated in a groove formed in the cylinder andwhich extends the length of the groove. Mounting bars are spaced end toend above the supporting plate, each of the mounting bars having aclamping rail for holding the edge of a printing plate and the mountingbars being captively shiftable on the supporting plate. Each mountingbar has provision for circumferential and axial adjustment. Thesupporting plate is clamped in the bottom of the groove by readilyaccessible screws which permit removal, as a unit, of the supportingplate, the captive mounting bars, and associated parts. This permitssubstitution of an alternative single, elongated mounting bar foraccommodating a single plate which extends the length of the groove.

1 Claim, 6 Drawing Figures PATENTEU M2 @1975 SHEET 3 U? 4 DEVICE FORFASTENING FLEXIBLE PRINTING PLATES It is an object of the presentinvention to provide a plate lock-up mechanism for flexible printingplates which permits a plurality of plates to be individually securedand adjusted in side-by-side relation and which permits alternateaccommodation, on the same cylinder, of a single printing plate whichextends substantially the full length of the cylinder.

It is a more specific object of the present invention to provide a platelockup mechanism which is distinguished by the use of a supporting platewhich runs the length of the groove and which has a plurality ofprinting plate mounting bars captive thereon with means for individualcircumferential and axial adjustment, with the supporting plate andcaptive mounting bars being removable from the cylinder as a unit byloosening a few screws so that a single printing plate mounting bar maybe alternatively mounted in place easily and quickly as a singlemechanical step without exercise of skill.

It is another specific object of the invention to provide a supportingplate construction distinguished by an L cross section and having aplurality of plate mounting bars which are individually biased and inwhich the supporting plate and mounting bars, together with the biasingmeans, may all be removed as a unit from the cylinder without affectingthe biasing forces.

Other objects and advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawings in which:

FIG. 1 is a plan view of a plate lock-up mechanism constructed inaccordance with the present invention with provision for mounting threeplates side by side on a plate cylinder.

FIG. 2 is a fragmentary transverse section taken along the line 22 inFIG. 3.

FIG. 3 is a fragmentary plan view showing a portion of one of themounting bars.

FIG. 4 is a fragmentary elevational view looking along the line 44 inFIG. 3.

FIG. 5 is a fragmentary section looking along the line 55 in FIG. 3.

FIG. 6 is a fragmentary view corresponding to FIG. 5 but showing thesubstitution, in the groove, of a single plate mounting bar.

While the invention has been described in connection with a preferredembodiment, it will be understood that I do not intend to be limited tothe particular embodiment shown but intend, on the contrary, to coverthe various alternative and equivalent forms of the invention includedwithin the spirit and scope of the appended claims.

Turning now to the drawings, there is shown a portion of a printingcylinder 10. This cylinder will be understood to form a part of aconventional lithographic printing unit consisting of a printingcylinder, blanket cylinder and impression cylinder, which latter havenot been illustrated. Formed in the printing cylinder is alongitudinally extending groove 11 having parallel side walls 12, 13,end walls 14, 15, and a flat bottom wall 16.

Mounted in the groove are plate mounting bars 21, 22, 23 for holding theends of flexible printing plates 24, 25, 26, respectively, the threeplates, in the present embodiment, being arranged side by side. Forsecuring and adjusting the other ends of these plates, similar mountingbars 27, 28, 29 are provided. Since all of the mounting bars are ofsimilar construction, it will suffice to take the bar 21 by way ofexample, as set forth in some detail in FIGS. 2, 3 and 4.

To grip the end of the plate 24 against the mounting bar 21, there issuperimposed, upon the bar, a coextensive clamping rail 31 which isloosely secured to the bar by means of a set of screws 32 and which hasa clamping lip 33 as well as a heel 34. Mounted under the heel 34, andbearing against the bar 21, is a non-circular, or eccentric, shaft 35having a capstan 36 at its end. It will be apparent that rotating thecapstan twists the shaft 35 to cam the heel of the clamping railupwardly which serves to rock the rail so as to bring the lip 33 tightlydown against the engaged end of the plate.

It is one of the primary features of the present inven tion that themounting bars 21-23 rather than being mounted directly in the groove 11are, instead, mounted upon an interposed supporting plate which extendsthe length of the groove. Thus I provide a supporting plate 40 having ahorizontal portion 41 and a vertical portion 42 to define an L shape.The portion 41 of the supporting plate is of flat construction seatingflatly in the bottom of the groove. Preferably, the supporting plate isprovided with integral pedestals 43 of shallow dimension which engagemounting pads 44 having machined surfaces spaced registeringly on thebottom of the groove.

For the purpose of maintaining the mounting bar 21 captive against theeffect of centrifugal forces while permitting limited circumferentialand axial movement required for register of the plate, a pair of guidebars, individually indicated at 50, are interposed between the mountingbar 21 and the horizontal portion 41 of the supporting plate. Each guidebar 50 is secured by a pair of screws 51 to the horizontal portion 41 ofthe supporting plate, with its length dimension oriented circumferentially as shown in FIG. 3. The guide bar is of inverted L shape,(FIGS. 4 and 5), having a horizontal or lip portion 52 which is receivedin an oversized, circumferentially extending groove 53 formed on theunderside of the mounting bar. To keep the guide bar captive in suchgroove, a retaining member 55 is provided, which is held in place by apair of screws 56. It will be apparent, then, that the mounting bar 21may be shifted circumferentially along the guide bar and may, inaddition, be shifted axially with respect to the guide bar andsupporting plate while still remaining securely captive.

In order to adjust the position of the mounting bar 21 with respect tothe supporting plate, a pair of adjusting screws 60 arecircumferentially threaded into the bar at its respective ends, eachscrew having a head 61, a tip 62 and a locking nut 63.

In accordance with one of the aspects of the present invention biasingsprings are interposed between the supporting plate and mounting bar forbiasing the mounting bar in the direction of the printing plate so thatthe tips of the circumferential adjusting screws are continuouslybottomed against the vertical portion 42 of the supporting plate. Takingone of the springs, indicated at 70, by way of example, the spring isreceived in a circumferentially extending bore 71 formed in the mountingbar. The spring is supported at its left-hand end at the base 72 of thebore and is supported at its right-hand end upon a small bracket 73which is integral with the supporting plate 40. For guiding the spring,a pin or rod 74 is preferably telescoped within it, the right-hand endof the spring being seated upon the head 75 of the pin while the tip 76of the pin extends clear through a suitable clearance opening.

It will be apparent, then, that when the locking nuts 63 are loosenedand the circumferential adjusting screws 70 are turned in a clockwisedirection, the mounting bar will be shifted relatively away from thevertical portion 42 of the supporting plate and in a direction totension the printing plate. Or the screws may be turned in the oppositedirection. The adjusting screws 60, employed as a pair, may therefore beused to' register the printing plate in the circumferential direction,as well as tensioning it, and by adjusting the screws differentially, alimited amount of skew may be imparted to the plate as required undercertain conditions.

To adjust the mounting bar 21 endwise, that is, in the axial direction,adjusting screws are provided at the ends of the bar. Referring to theend of the bar visible in FIG. 3, an adjusting screw 80 is providedhaving a head 81 and a shank 82 which is axially threaded into the bar,the head engaging a land surface 83 at the end of the groove. A tightthread is used so that a locking nut may be dispensed with. Since theadjusting screws 60, 80 are arranged at right angles to one another,axial and circumferential adjustment may be imparted to the barindividually.

To enable axial adjustment of all of the mounting bars, while at thesame time taking up end play between them, additional axial adjustingscrews 85, 86 interposed between the opposed spaced ends of the bars asshown in FIG. 1.

In carrying out the present invention, a readily accessible set ofscrews is provided for clamping the mounting plate 40 in the bottom ofthe groove, with the vertical portion 42 of the plate flatly seatedagainst the groove sidewall. The screws for the supporting plate, whichare preferably socket-headed, and indicated at 90, are provided in pairsand spaced on opposite sides of the mounting bar and well clear thereofso as to permit direct access by a turning tool which may, conveniently,be in the form of an Allen type wrench.

Thus, when it is desired to accommodate a single printing plate whichextends the length of the groove in the cylinder, rather than employingthe three narrower printing plates in side-by-side relation, the screws90 are unscrewed, thereby freeing the supporting plate 40 so that it maybe lifted from the groove, with all of the locking mechanism thereon, asa unit. It is to be particularly noted that when the mechanism is thusremoved it is removed complete with the (a) series of mounting bars, (b)the guide bars which hold the mounting bars captive, (c) the rails andclamping means for the rails and (d) the biasing springs, without anynecessity for releasing the biasing forces. The biasing forces remaininternally confined between the vertical portion 42 of the supportingplate and the opposed brackets 73, along the opposite edge of thesupporting plate and which are integral with it. It is also to be notedthat the entire assembly may be removed, following disengagement of theplate, without having to disturb any of the circumferential or axialadjusting screws.

With the unitary lock-up mechanism removed, it may be replaced by asingle plate mounting bar which extends the length of the groove andwhich is believed to be adequately shown in FIG. 6. Here it will benoted that the single, elongated mounting bar 21a is mounted upon aguide bar a held in place by a pair of screws 51a (only one of which isshown) which serve to clamp the guide bar directly against the pad 44previously referred to and which is formed on the bottom of the cylindergroove. The guide bar 50a has a horizontally extending portion 52a whichis registeringly received in an oversized groove 53a, with the guide barbeing held captive in the groove by means of a retainer 55a which issecured to the bar by a pair of screws 56a. Identical guide bars 50a maybe spaced at convenient intervals.

For the purpose of registering and tensioning the single plate 240 whichis engaged by the bar 22a, circumferential adjusting screws are threadedinto the bar adjacent its ends, adjusting screws which are similar tothe adjusting screws 60 previously described, with the difference thatthe tips of the screws, instead of engaging a supporting plate, willdirectly engage the sidewall 12 of the groove. For the purpose ofadjusting the mounting bar 21a endwise, it will be understood that axialadjusting screws (not shown) are provided at the respective ends of thebar and which are similar to the axial adjusting screws 80 describedabove.

In addition to the flexibility provided by the threeacross lock-upillustrated in FIG. 1 and the single bar lock-up alternatively used andindicated in FIG. 6, it will be understood that the flexibility may beextended to include supporting plates having different numbers ofmounting bars; for example, an assembly may be provided similar to thatshown in FIG. 1 but which has two, rather than three, plate mountingbars for mounting of plates two-across.

While the discussion has been restricted to a lock-up mechanism forengaging corresponding ends of a set of printing plates, it will beunderstood that a similar lockup assembly may be symmetrically provided,in the same groove in the cylinder, for engaging the opposite ends ofthe same plates or for engaging the ends of a second set of plates wherethe cylinder has a second groove and where plates are mounted twoaround. Corresponding reference numerals are used, for convenience, todesignate corresponding parts of the second mechanism.

It is preferred to provide a supporting plate 40 which is of Lconfiguration for a number of reasons. Such configuration not onlymaintains the biasing forces exerted by the spring self-contained, asdiscussed, but itis of high inherent strength and more protective of themechanism once it is removed from the cylinder.

In installation of a typical plate, the leading and trailing edges aresecurely clamped by respective clamping rails 31. One end of the platemay be then registered, both circumferentially and axially, by turningthe screws 60, 80. Following this the axial screws at the other end ofthe plate may be adjusted and then, as a final step, the circumferentialscrews at the other end of the plate may be tightened as necessary toimpart the desired degree of tension, following which the lock nuts areturned tight to preserve the adjustment.

What is claimed is:

1. In a plate lock-up mechanism for securing and adjusting a flexibleprinting plate upon a plate cylinder which has a longitudinal grooveformed therein defined by side walls, end walls and generally flatbottom wall, the combination comprising a supporting plate member of Lcross section made up of horizontal and vertical portions at rightangles to one another respectively seated against the bottom and sidewall of the groove and extending substantially the length thereof, thesupporting plate member having bracket means along one edge in spacedopposition to the vertical portion, a plurality of mounting bars spacedend to end in the groove above the supporting plate member, meansincluding guide bars interposed between the mounting bars and thesupporting plate member for holding the mounting bars individuallycaptive thereon while permitting limited shifting movement bothcircumferentially and axially, each of the mounting bars having acoextensive rail for tightly holding the edge of a printing plate,circumferentially oriented springs interposingly compressed between thebracket means and the individual mounting bars for biasing the mountingbars circumferentially in the direction of the vertical portion of thesupporting plate member, first screw means in each bar extendingcircumferentially bearing against the vertical portion of the supportingplate member for adjusting each bar and its printing platecircumferentially with respect to the cylinder, second screw means ineach bar for adjusting each bar and plate axially with respect to thecylinder, and a set of supporting screws for clamping the supportingplate member securely against the bottom of the groove, the supportingplate screws being positioned such that the axes of the screws, whenextended past the head ends of the screws, are substantially free of anyobstruction by any other part of the plate lock-up mechanism so that thescrews are readily accessible for easy and unobstructed application ofan unscrewing tool notwithstanding the presence of the plate mountingbars whereby, upon removal of the screws, the supporting plate memberand the mounting bars and associated biasing springs which are captivethereon may be removed as a unit from the cylinder while preserving theadjusted positions of the bars relative to the supporting plate memberand while preserving the compressed condition of the biasing springs forsubstitution in the groove of a single plate mounting bar extending thelength thereof.

1. In a plate lock-up mechanism for securing and adjusting a flexibleprinting plate upon a plate cylinder which has a longitudinal grooveformed therein defined by side walls, end walls and generally flatbottom wall, the combination comprising a supporting plate member of Lcross section made up of horizontal and vertical portions at rightangles to one another respectively seated against the bottom and sidewall of the groove and extending substantially the length thereof, thesupporting plate member having bracket means along one edge in spacedopposition to the vertical portion, a plurality of mounting bars spacedend to end in the groove above the supporting plate member, meansincluding guide bars interposed between the mounting bars and thesupporting plate member for holding the mounting bars individuallycaptive thereon while permitting limited shifTing movement bothcircumferentially and axially, each of the mounting bars having acoextensive rail for tightly holding the edge of a printing plate,circumferentially oriented springs interposingly compressed between thebracket means and the individual mounting bars for biasing the mountingbars circumferentially in the direction of the vertical portion of thesupporting plate member, first screw means in each bar extendingcircumferentially bearing against the vertical portion of the supportingplate member for adjusting each bar and its printing platecircumferentially with respect to the cylinder, second screw means ineach bar for adjusting each bar and plate axially with respect to thecylinder, and a set of supporting screws for clamping the supportingplate member securely against the bottom of the groove, the supportingplate screws being positioned such that the axes of the screws, whenextended past the head ends of the screws, are substantially free of anyobstruction by any other part of the plate lock-up mechanism so that thescrews are readily accessible for easy and unobstructed application ofan unscrewing tool notwithstanding the presence of the plate mountingbars whereby, upon removal of the screws, the supporting plate memberand the mounting bars and associated biasing springs which are captivethereon may be removed as a unit from the cylinder while preserving theadjusted positions of the bars relative to the supporting plate memberand while preserving the compressed condition of the biasing springs forsubstitution in the groove of a single plate mounting bar extending thelength thereof.